There are two closely related goals for the proposed research. The first goal is to better understand the visual mechanisms which underlay the differences in spatial and temporal properties of color and luminance coding in normal observers. The second goal is to understand the abnormalities in these properties which occur in some color deficient observers. Psychophysical experiments will be used to study the effects of light adaptation on the spatial and temporal properties of color and luminance coding, and to determine how color and luminance coding vary with retinal location. There are two purposes to these experiments. The spatial and temporal properties of color coding clearly differ from those of luminance coding in normal observers. The first purpose is to evaluate possible models of the neural mechanisms which underlay the differences in color and luminance coding in normal observers. The second purpose of these experiments is to further understand the abnormalities in the neural coding of color information which occur in some congenital color deficient observers. The proposed research should have direct significance for theories about the mechanisms of color and luminance coding as well as impact of clinical psychophysical testing of visual defects, the testing of color vision capabilities for practical applications, and the genetics of color deficiencies.